Coupler

ABSTRACT

A coupler for a rail wagon includes a coupler body. The body includes a shank and a head located at an end of the shank. A coupler latch member is mounted to an end of the head. The latch member includes a protruding portion for receipt in a recess of the head. The protruding portion includes at least two adjacent projecting lugs, and the recess includes at least two corresponding adjacent shoulders behind which each lug is located when the latch member protruding portion is received in the head recess.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national stage application under 35 USC 371 of International Application No. PCT/AU2011/001048, filed Aug. 17, 2011, which claims the priority of Australian Application No. AU 2010903691, filed Aug. 17, 2010, the contents of which prior applications are incorporated herein by reference.

FIELD OF THE INVENTION

An improved coupler for a rail wagon is disclosed. The coupler can take the form of an automatic-type coupler which automatically latches with an opposing coupler to join the two wagons when they are buffed together. The coupler can transmit both buff (compressive) and draw (tensile) loads between the wagons in use.

BACKGROUND OF THE INVENTION

In the deployment of rail wagons, draw loads are often responsible for fatigue failure in the coupler. These draw loads are transmitted through a so-called knuckle and into a body of the coupler, via a single upper pulling lug and a single lower pulling lug. These pulling lugs comprise flanges in the knuckle that mate with load bearing flanges in a head of the coupler. The load at the knuckle is then transmitted through the shank of the coupler to the remaining drawgear assembly and into the wagon structure. A dominant premature fatigue location in the coupler head is at the lower pulling lug. Another dominant failure mechanism of the coupler assembly is fatigue failure of the knuckle through its so-called knuckle “palm”.

The above references to the background art do not constitute an admission that the art forms a part of the common general knowledge of a person of ordinary skill in the art. The above references are also not intended to limit the application of the coupler disclosed herein.

SUMMARY OF THE INVENTION

In accordance with a first aspect there is disclosed a coupler for a rail wagon. The coupler comprises a coupler body, with the body comprising a shank for mounting to a drawgear assembly contained within the wagon structure. A head is located at an end of the shank, and a coupler latch member can be mounted to an end of the head for latching onto a corresponding latch member mounted to a coupler of an adjacent rail wagon. This latch member is sometimes referred to as a “knuckle”.

In accordance with the first aspect the latch member comprises a protruding portion for receipt in a recess of the head. The protruding portion comprises at least two adjacent projecting lugs, and the recess comprises at least two corresponding adjacent shoulders behind which each lug is located when the latch member protruding portion is received in the head recess. Such a configuration can increase the bearing area between the latch member and the coupler head, to increase the coupler's load capacity, to prolong its life and to extend its fatigue resistance. Such a configuration can also significantly reduce the concentration of stress during wagon draw in the vicinity of the lower interface between the latch member and the coupler head.

In accordance with a second aspect the latch member comprises a protruding portion for receipt in a recess of the head. An elongate lateral lug projects to the side of the protruding portion in use. The lateral lug comprises an engagement surface that faces back to the latch member. In use, the lateral lug engagement surface faces a corresponding engagement face located within the head recess. Again, the lateral lug can increase the bearing area between the latch member and the coupler head, to increase the coupler's load capacity and to prolong its life, to extend its fatigue resistance, and to also reduce the concentration of stress during wagon draw.

The lateral lug of the second aspect can be employed together with the at least two adjacent projecting lugs of the first aspect to further increase the bearing area between the latch member and the coupler head in use.

In accordance with a third aspect the coupler head comprises spaced opposing bearing lugs that protrude from an end of the head in a clevis configuration, with the latch member being pivotally mountable to the head in use via these bearing lugs. During wagon draw, the clevis configuration has been observed to better distribute the load and stresses between the latch member and the coupler head. The clevis configuration also improves stress distribution through the latch member itself, reducing peak stresses in the “palm” of the latch member (the palm being a predominant initiation point for both fatigue and overload failure of the latch member). This in-turn improves both the latch member's fatigue life and also its ultimate strength/capacity.

This clevis configuration of the bearing lugs can be employed with the lateral lug of the second aspect and the at least two adjacent projecting lugs of the first aspect, to further and better distribute the load and stresses between the latch member and the coupler head in use. More particularly, the clevis configuration can take load away from this the “palm” of the latch member, significantly increasing its capacity and fatigue life.

In accordance with the third aspect the latch member can be pivotally mounted to the head via opposing pins that connect respective bearing projections located at opposite ends of the latch member to the bearing lugs. The pins can extend along an elongate axis of the latch member.

In one form of the clevis configuration the pins can be configured to act as both load bearing members and the pivot point for the latch member.

In another form of the clevis configuration, a respective load bearing flange can be provided in the head to in use surround a bore area for each pin. In this form, a lighter pin (e.g. with a smaller diameter) can be employed that acts solely as the pivot point for the latch member. The load bearing flanges are able to act in a similar manner to the pulling lugs in better distributing load and reducing fatigue failure, in that mating flanges can be provided on both the latch member and the coupler head.

In one form, first and second adjacent projecting lugs may extend in use downwardly from the protruding portion, though it should be noted that, if more than two adjacent downwardly extending lugs are employed, then the bearing area and distribution of stresses can be further increased. It should also be noted that, two or more adjacent in-use upwardly extending lugs can be employed, again to further increase the bearing area and thus the distribution of stresses.

The first lug can project from an end of the protruding portion and can locate in use in a first transverse recess located within the head recess that defines a first of the shoulders. The second lug can project from the protruding portion at a location inset from the first lug. The second lug can locate in use in a second transverse recess located within the head recess adjacent to the first transverse recess, with the second transverse recess defining a second of the shoulders.

In this form, each of the first and second lugs can be elongate and curved, and can comprise a curved planar engagement surface that faces back to the latch member. Each lug can locate in a correspondingly curved transverse recess that defines a corresponding curved planar engagement face forming part of the shoulder. When the latch member pivots in use (i.e. during latching), the curvature of the lugs and recesses allows the protruding portion to sweep back and forth within the head recess

In one form, the coupler can further comprise an upper projecting lug that extends in use upwardly from the protruding portion. Again, the upper lug may be elongate and curved, and may comprise a curved planar engagement surface that faces back to the latch member. The upper lug can engage a correspondingly curved engagement surface defined within the head recess. Again, these curvatures can allow the protruding portion to sweep back and forth within the head recess (i.e. during latching).

In this form, the upper projecting lug can be extended so as to become contiguous with the lateral lug. Yet again, this can further strengthen and increase the bearing area between the latch member and the coupler head in use.

In a further variation more than one upper pulling lug can be employed. A second (or further) upper pulling lug(s) can further spread the distribution of draw loads in use of the latch member.

Thus, in accordance with a fourth aspect, the latch member comprises a protruding portion for receipt in a recess of the head. The protruding portion comprises at least two adjacent in-use upwardly projecting lugs, and the recess comprises at least two corresponding adjacent shoulders behind which each lug is located when the latch member protruding portion is received in the head recess. Again, such a configuration can increase the bearing area between the latch member and the coupler head, to increase the coupler's load capacity, to prolong its life and to extend its fatigue resistance. Again, the two upwardly projecting lugs can increase the bearing area between the latch member and the coupler head, to increase the coupler's load capacity and to prolong its life, to extend its fatigue resistance, and to also reduce the concentration of stress during wagon draw.

The at least two upwardly projecting lugs of the fourth aspect can be employed together with the clevis configuration of the third aspect, with the lateral lug of the second aspect, and with at least two downwardly projecting lugs, to further and better distribute the load and stresses between the latch member and the coupler head in use.

In one form, the latch member is elongate and is mounted to the head so as to pivot around an elongate axis of the latch member, with the protruding portion extending laterally from the latch member with respect to its elongate axis.

In one form, in use of the coupler with a rail wagon, the latch member can have an elongate axis that extends vertically and the protruding portion can extend generally horizontally into the head.

In a fifth aspect the coupler further comprises a locking block for location in the head recess between the latch member protruding portion and the head. During coupling with another (i.e. like) latch member, the locking block is adapted to drop into a closed (latch member-latched) position, and then restrain the latch member in that position.

In accordance with the fifth aspect the locking block comprises a planar face for engaging a surface of the latch member protruding portion. The locking block planar face comprises a reverse taper with respect to a direction of insertion of the locking block into the head recess, with the latch member surface being correspondingly tapered, for a mating interface in the closed (latched) position.

This mating interface, which arises from the correspondingly tapered surfaces inter-engaging, has been observed to address fitment issues that arise from either undersize or oversize blocks.

In this regard, the block is able to drop into the locked position, with the tapered mating faces always contacting each other. Block oversize and undersize issues can arise during block manufacture. In the case of an oversize block, the block will drop in to a lesser extent, and in the case of an undersize block the block will drop further before coming to a wedged, locked position. However, the tapered locking block is able to drop over the life of the coupler, compensating for wear on the fit faces, and maintaining a slack-less, locked condition. Reducing or eliminating slack in the latch locking mechanism has been observed to reduce dynamic impulse loads during coupler service. This reduction in dynamic loads improves the fatigue life, not only of coupler components, but also of other drawgear components. Thus, the block is able to form a tight fit, and can continue to restrain the latch member in the closed position, over time.

In one form the locking block can comprise first and second planar (i.e. two) faces for respectively engaging the latch member protruding portion surface and the head surface. Each of the first and second planar faces can be provided with a reverse taper, and each of the latch member surface and head surface can be respectively and correspondingly tapered for a mating interface.

In accordance with a sixth aspect a rail wagon can be provided that is fitted with a coupler according to any one of the preceding first to fourth aspects.

In accordance with a seventh aspect there is disclosed a latch member for mounting to a head of a rail wagon coupler. The latch member comprises a protruding portion for receipt in a recess of the head. The protruding portion comprises at least two adjacent projecting lugs, with each lug able to be located behind at least two corresponding adjacent shoulders when the latch member protruding portion is received in the head recess. The latch member of the sixth aspect can be otherwise as defined above.

In accordance with an eighth aspect there is disclosed a latch member for mounting to a head of a rail wagon coupler. The latch member comprises a protruding portion for receipt in a recess of the head. An elongate lateral lug projects to the side of the protruding portion in use. The lateral lug comprises an engagement surface that faces back to the latch member, with the lateral lug engagement surface being arranged in use to engage a corresponding engagement face located within the head recess. The latch member of the eighth aspect can be otherwise as defined above.

In accordance with a ninth aspect there is disclosed a latch member for mounting to a head of a rail wagon coupler. The head comprises spaced opposing bearing lugs that protrude therefrom. The latch member comprises correspondingly spaced opposing bearing projections for mounting to the bearing lugs.

In the ninth aspect the head bearing lugs can protrude therefrom in a clevis configuration. The latch member bearing projections can locate adjacent to and outside of opposite end faces of the head bearing lugs. Opposing pins can then be employed to secure a respective adjacent bearing lug to a bearing projection. The latch member can pivot around an axis extending through the pins.

The latch member of the ninth aspect can be otherwise as defined above. In this regard, the clevis configuration can comprise respective load bearing flanges, or the pins can be configured to act as both load bearing members and the pivot point for the latch member.

In a tenth aspect there is disclosed a locking block for location in a recess defined in a head of a rail wagon coupler. The locking block drops into position when the latch member is first rotated into the closed position. In this locked position the locking block contacts against a protruding portion of a latch member located in the head recess so as to restrain the latch member in the closed (latched) position in use.

In accordance with the tenth aspect the locking block comprises a planar face for respectively engaging a surface of the latch member protruding portion. The planar face has a reverse taper with respect to its direction of insertion into the head recess, with the latch member surface being correspondingly tapered for a mating interface in use.

In one embodiment the locking block may comprise two planar tapered faces, one for respectively engaging the surface of the latch member protruding portion and one for respectively engaging the surface of the head.

In this regard, in use, and when the coupler is generally horizontal, the block face that engages the latch member can be inclined to a vertical plane but be generally parallel to a longitudinal axis through the coupler, and the block face that engages the head can be aligned with the vertical plane but be generally inclined to the coupler longitudinal axis. This orientation of the faces can aid with block insertion, and can accommodate block imperfections (i.e. that may arise from block manufacture). The locking block of the tenth aspect can be otherwise as defined above.

BRIEF DESCRIPTION OF THE DRAWINGS

Notwithstanding any other forms which may fall within the scope of the coupler, latch member and locking block as defined in the Summary, specific embodiments will now be described, by way of example only, with reference to the accompanying drawings in which:

FIG. 1 shows a perspective view of a first coupler embodiment;

FIGS. 2A to 2D respectively show side, front, plan and reverse-side views of the coupler of FIG. 1;

FIGS. 3A to 3D respectively show four different sectional views through the coupler of FIG. 2, taken on the lines A-A, B-B, C-C and D-D, (though with line D-D taken on FIG. 3B);

FIG. 4 shows a similar section through the coupler to FIG. 3B;

FIG. 5 shows a similar section through the coupler to FIG. 3A;

FIG. 6 shows a similar section through the coupler to FIG. 3D;

FIG. 7 shows a similar view of the coupler to FIG. 2A;

FIG. 8 shows a similar section through the coupler to FIG. 3C;

FIGS. 9A to 9C respectively show side, underside plan and sectional views of the latch member for use with the coupler of FIG. 1, (with the section of FIG. 9C taken on the line C-C of FIG. 9A);

FIGS. 10A and 10B respectively show front and plan views of the locking block for use with the coupler of FIG. 1;

FIGS. 11A and 11B respectively show a plan and sectional view (on the line F-F) of the coupler of FIG. 1 when in an open (unlatched) configuration;

FIGS. 12A and 12B show similar views to FIG. 11 but when the coupler is in a closed (latched) configuration;

FIG. 13 shows a sectional view through the coupler to illustrate a first clevis-pin mounting pivot configuration;

FIG. 14 shows a sectional view through the coupler to illustrate a second alternative clevis-pin mounting pivot configuration; and

FIGS. 15A and 15B respectively show side and plan views of the latch member, for use with the coupler of FIG. 1, to illustrate the “palm” region (X-Y) thereof.

DETAILED DESCRIPTION OF THE INVENTION

Referring firstly to FIG. 1, a rail wagon coupler 10 includes a coupler body 12 cast as a single unit from alloyed steel. The body 12 comprises a shank 14 and an integral head 16 located at an end of the shank 14. A coupler latch member in the form of a knuckle 18 is pivotally mounted to an end of the head 16. The knuckle 18 comprises a latching portion 19 extending from an elongate knuckle body 20 that pivots on the head about an elongate axis. The knuckle is also cast as a single unit from alloyed steel, though the grade may vary (e.g. be improved) from that employed for the coupler body.

Coupler 10 is an automatic-type coupler, in that it automatically latches (i.e. via latching portion 19) with an opposing like-coupler when two rail wagons are buffed together. The coupler functions to join the two wagons and in use transmits both buff (compressive) and draw (tensile) loads between the wagons. The draw loads are the main loads responsible for fatigue failures in the coupler. The draw loads are transmitted through each knuckle 18 and into each respective coupler body 12. The load is transmitted via the coupler shank 14 to a drawgear assembly (not shown) and into the wagon structure.

The knuckle 18 comprises a protruding portion in the form of a knuckle tail 21 which is received in a recess 22 formed in the head 16. An alloy steel locking block 24 drops into the recess under gravity. The block 24 acts as a restraining wedge against the knuckle tail 21 to restrain the knuckle 18 in a closed (latched) orientation in use.

To better illustrate how automatic coupling occurs, FIG. 11 shows the knuckle 18 in an open (ready-to-be-latched) position and FIG. 12 shows the knuckle 18 in a closed (latched) position. In use, when two couplers in the open position (FIG. 11) are buffed together, the contact with the opposing knuckles 18 causes them to rotate into the latched position. Once the knuckle has moved into the latched position, the locking block 24 drops into place, restraining the knuckle tail 21 and preventing the knuckle from pivoting open. When the coupler needs to be opened again (e.g. at the end of a journey to uncouple two couplers) an internal mechanism is activated to lift the block 24 out of the recess, allowing the knuckle to pivot open again.

The draw loads transmitted through each knuckle 18 to the head 16 occur via upper and lower pulling lugs (which will be described in greater detail below). These pulling lugs function as load bearing flanges in the coupler head and as mating flanges in the knuckle.

The following unique features of the coupler have been developed to increase the coupler's load capacity and to prolong its fatigue life. These features can be summarised as:

Tandem Pulling Lugs—FIGS. 3A and 5 show first and second lower pulling lugs 30 and 32. The provision of two (or more) pulling lugs at least doubles the load bearing area and thus significantly reduces stress concentration in the knuckle-to-head connection. As described below, two (or more) upper pulling lugs can be provided (usually in addition to the lower pulling lugs, rather than as an alternative thereto).

Addition of Vertical Pulling Lug—FIGS. 3B and 4 show horizontal sections through the coupler and highlight an additional bearing face in the form of a vertical pulling lug 34 that has been introduced into the coupler. This lug further increases the bearing area of the coupler in the knuckle-to-head connection.

Extension of Upper Pulling Lug—FIGS. 3D, 6 and 9C show vertical sections through the coupler and knuckle respectively and highlight how the upper pulling lug 36 has been laterally extended to increase the bearing area of the coupler in the knuckle-to-head connection. Further, the lateral extension of the upper pulling lug 36 enables it to be made contiguous with the vertical pulling lug 34, to further increase lug strength and to provide a continuous bearing surface from upper to lateral.

Load Bearing Knuckle Pivot Pin—FIGS. 3A, 7, 9C and 13 show the knuckle and coupler head modified to include two shorter pins 40 & 42 that are utilised in a load bearing configuration. In this regard, as best shown in FIGS. 3A & 7, the coupler head 16 is modified into a clevis configuration 44. The clevis configuration introduces another load path between the knuckle and the coupler body (i.e. in addition to the upper and lower pulling lugs). Again, this significantly reduces stress concentrations in both the coupler body and the knuckle, increasing the load bearing capacity of both components.

Alternative Load Bearing Clevis—FIG. 14 shows the knuckle 18 and a coupler head clevis configuration 44′ that is modified to include a single lighter, smaller diameter pin 70. The pin 70 is employed as a pivot only, with a clearance fit CF being employed in the bore 72 to make the pin 70 a non-load bearing member. The single, long, non-load bearing pin 70 extends the full depth of the bore 72. In the modified clevis configuration 44′ at least one load bearing lip 74 is formed in the knuckle 18 around the pin bore with the coupler head 16 defining upper and lower mating bosses 76 around the pin bore. The lip and boss interface at region 78, which now provides the load bearing function in the clevis configuration. Thus, the pin 70 is able to perform the sole function of acting as a pivot for knuckle opening and closing. Again, the modified clevis configuration 44′ provides another load path between the knuckle and the coupler body to significantly reduce stress concentrations in both the coupler body and the knuckle, and increase their load bearing capacity.

Both clevis configurations 44 and 44′ can redistribute load away from the ‘palm’ area of the knuckle, in addition to providing a secondary load path from the knuckle into the body. This reduces peak stresses in both the knuckle palm and the coupler pulling lugs. The knuckle palm area PA is depicted using cross-hatching in FIG. 15, extending over region X to Y. Fatigue cracks frequently originate from the X-Y face and propagate normal to the face through the cross-section of the knuckle. This region represents the weakest area in the total coupler assembly and the modified load bearing clevis configurations 44 and 44′ take load away from this face, as well as from the pulling lugs, significantly increasing knuckle capacity and fatigue life.

Tapered Locking Block—FIGS. 1, 3C, 8, 10, 11 and 12 show the locking block 24, which functions to restrain the knuckle 18 in the closed (i.e. latched) position. In use, when a locking block has two vertical sides, two problems arise:

1. Where the distance between the two sides is oversize the locking block is too large to be dropped into position between the knuckle tail and the coupler body to hold the knuckle closed.

2. Where the distance between the two sides is too small the locking block will operate correctly but will result in a “slack” arising in the coupler at the knuckle, leading to unnecessarily high dynamic loads during buff or draw.

The taper applied at block face 60 functions to eliminate both oversize block fitment issues and undersize block slack issues. The taper applied at each of block faces 60 and 62 functions to give the locking block higher “tolerance” in use. Furthermore the taper arrangement allows the block to continue to drop over the life of the coupler, compensating for wear on the mating faces, and maintaining a “slackless” fit within the coupler head.

Each of the above features will now be described in greater detail:

Lower Pulling Lug

Referring now to FIGS. 3A, 5 and 9B, the coupler 10 can be modified to increase overall knuckle-to-head bearing area. For example, the coupler can be provided with the first and second lower pulling lugs 30 and 32. The first and second lugs are adjacent to each other and extend downwardly in use from the knuckle tail 21.

As shown in FIG. 9B, the first lug 30 is elongate and curved, and is located to project from an end of the tail 21 to be received in use in a first transversely extending curved recess 37 located within the head recess 22. Recess 37 defines a first shoulder (see FIG. 3A) that retains the lug 30 therebehind.

The second lug 32 projects from the tail 21 at a location that is inset from the first lug 30. As also shown in FIG. 9B, the second lug 32 is also elongate and curved, and is received in use in a second transversely extending curved recess 38 located within the head recess 22. The second recess 38 defines a second shoulder (see FIG. 3A) that retains the lug 32 therebehind.

The bearing area is primarily between an inside curved face of each of the first and second lugs 30 and 32, and a corresponding matching curved faces defined within each of the first and second recesses 37, 38. By introducing a second lower pulling lug, the bearing area is effectively doubled.

The elongate curvature of the lugs 30, 32 and recesses 37, 38 allows the knuckle 18 to pivot in clevis 44 when the knuckle latches with an adjacent knuckle in service. In this regard, the tail 21 sweeps back and forth within the head recess 22, and is restrained in the locked (block-engaged) position once the locking block 24 has dropped into the cavity.

It should be noted that if more than two downwardly extending lugs are employed then the bearing area and distribution of stresses can be further increased, although the head and knuckle tail configurations become more complex.

Vertical Pulling Lug

Referring now to FIGS. 3B and 4, the newly introduced vertical pulling lug 34 is incorporated as part of the knuckle 18 and protrudes from a proximal part of the tail 21. The lug 34 faces against a corresponding vertical formation 39 forming part of the head 16 (i.e. located within the head recess 22). This lug further increases the bearing area of the knuckle with respect to the head at the knuckle-to-head connection.

Upper Pulling Lug

Referring now to FIGS. 3A, 3D, 6 and 9C, it will be seen that the upper pulling lug 36 has been laterally extended (i.e. lengthened both to the left and right in FIG. 3D) to increase its bearing area at the knuckle-to-head connection.

Again, the upper lug 36 is elongate, and is curved to facilitate back-and-forth pivoting of the knuckle 18. The lug 36 projects upwardly from the tail 21 and is retained behind a correspondingly curved shoulder 36A located within the head recess 22 (FIG. 3A).

Further, as best shown in FIGS. 3D and 6, the lateral extension of the upper lug 36 enables it to be formed contiguously (integrally) with the vertical pulling lug 34, with the “combined” lug having increased strength and providing an increased and continuous bearing surface, extending from an upper part of the tail to a lateral part of the tail.

It should also be noted that two (or more) upper pulling lugs can be provided to increase overall knuckle-to-head bearing area, and thus the distribution of stresses. For example, the coupler can be provided with the first and second upper pulling lugs can be located adjacent to each other and extend upwardly in use from the knuckle tail 21 to be retained behind correspondingly curved shoulders located within the head recess 22.

Knuckle Pivot Pins & Clevis Head

Referring now to FIGS. 3A, 7, 9C 13 and 14, both the knuckle 18 and the coupler head 16 are modified to allow either two short pivot & heavy-duty shear pins 40 and 42 to be utilised, or to utilise a single, long non-load-bearing pin 70, in alternative improved load bearing configurations.

FIGS. 3A, 3C, 7 and 13 most clearly depict the clevis configuration 44 employed at the coupler head 16. As outlined above, the clevis configuration 44 provides another load path between the knuckle and the coupler body to significantly reduce stress concentrations in both the coupler body and the knuckle, and increase their load bearing capacity.

The clevis configuration 44 comprises upper and lower bearing lugs 45 and 46 which extend out from upper and lower portions of the head. The knuckle body 20 comprises corresponding openings 47 and 48, defined by upper end lug 50 and lower end lug 51, with the upper and lower bearing lugs 45 and 46 being received in the openings 47 and 48.

Each of the upper end lug 50 and lower end lug 51 has an in-use vertical bore 52, 53 therethrough (see FIG. 9B) and into which a respective pin 40, 42 can be inserted. As best shown in FIGS. 3A and 3C, each pin 40, 42 in turn extends through an aligned bore in each of the upper and lower bearing lugs 45 and 46, with each pin end being received into a recess defined in the knuckle body 20. Each pin can be secured in place by a grub-type bolt at 54, 55, although alternate pin retention methods may also be employed.

Thus, the pins 40, 42 extend along an elongate axis of the knuckle body, such that they oppose each other at opposite sides of the clevis configuration 44.

FIG. 14 depicts the modified clevis configuration 44′ incorporating the load bearing lip/boss arrangement 74, 76, 78 around the knuckle pivot axis, which enables a single, more slender non-load bearing pin 70 to be used (i.e. as has already been described-above).

Locking Block

Referring now to FIGS. 1, 3C, 8, 10, 11 and 12, the locking block 24 is employed to hold the knuckle 18 in a closed (latched) position in service. In this regard, the block acts on the tail 21 to maintain the knuckle in the latched configuration, although the block is deformable to allow the knuckle to pivot when latching with a knuckle of an adjacent coupler.

The locking block 24 is modified to have a tapered face 60, which functions to eliminate both oversize block fitment issues and undersize block slack issues. In this regard, when the locking block 24 drops into position in the head recess 22, the tapered face 60 is brought into close-facing engagement with a corresponding surface located at the knuckle tail 21.

The block also includes a tapered face 62 which engages a correspondingly tapered face located within the head recess 22. Again, face 62 can accommodate for lesser block manufacturing tolerances.

In use and as best shown on FIGS. 10A and 10B, and when the coupler 10 extends generally horizontally from a drawgear assembly, the face 60 can be inclined to a vertical plane but be generally parallel to a longitudinal axis through the coupler, and the face 62 can be aligned with the vertical plane but be generally inclined to the coupler longitudinal axis.

Whilst specific coupler, latch member and locking block embodiments have been described, it should be appreciated that these may be embodied in other forms.

For example, it may be possible to increase the bearing areas by “upsizing” one or more of the various lugs described herein. The head would then be modified accordingly.

In the claims which follow, and in the preceding description, except where the context requires otherwise due to express language or necessary implication, the word “comprise” and variations such as “comprises” or “comprising” are used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the coupler, latch member and locking block as disclosed herein. 

1. A coupler for a rail wagon, the coupler comprising a coupler body, the body comprising a shank and a head located at an end of the shank, with a coupler latch member being mounted to an end of the head; wherein the latch member comprises a protruding portion for receipt in a recess of the head, the protruding portion comprises at least two adjacent projecting lugs, and the recess comprises at least two corresponding adjacent shoulders behind which each lug is located when the latch member protruding portion is received in the head recess.
 2. The coupler of claim 1, wherein first and second adjacent projecting lugs extend in use downwardly from the protruding portion, with the first lug projecting from an end of the protruding portion and being located in use in a first transverse recess located within the head recess that defines a first of the shoulders, and with the second lug projecting from the protruding portion at a location inset from the first lug, the second lug being located in use in a second transverse recess located within the head recess adjacent to the first transverse recess, the second transverse recess defining a second of the shoulders.
 3. The coupler of claim 2, wherein each of the first and second lugs are elongated and curved and comprise a curved planar engagement surface that faces back to the latch member, each lug for location in a correspondingly curved transverse recess that defines a corresponding curved planar engagement face forming part of the shoulder.
 4. The coupler of claim 1, further comprising an elongated lateral lug that projects to the side of the protruding portion, the lateral lug comprising a generally planar engagement surface that faces back to the latch member, with the lateral lug engagement surface in use facing a corresponding planar engagement face located within the head recess.
 5. The coupler of claim 4, further comprising an upper projecting lug that extends in use upwardly from the protruding portion, wherein the upper lug is elongated and curved and comprises a curved planar engagement surface that faces back to the latch member, the upper lug able to engage a correspondingly curved engagement surface defined within the head recess, and wherein the lateral lug is contiguous with the upper lug.
 6. The coupler of claim 1, further comprising a locking block for location in the head recess between the latch member protruding portion and the head, the locking block being adapted to restrain the latch member in a closed, latched position.
 7. The coupler of claim 6, wherein the locking block comprises a planar face for engaging a surface of the latch member protruding portion, and wherein the planar face has a reverse taper with respect to a direction of insertion of the locking block into the head recess, with the latch member surface being correspondingly tapered for a mating interface.
 8. The coupler of claim 1, wherein the latch member is elongated and is mounted to the head so as to pivot around an elongated axis of the latch member, with the protruding portion extending laterally from the latch member with respect to its elongated axis.
 9. The coupler of claim 8, wherein the latch member is pivotally mounted to the head via spaced opposing bearing lugs that protrude from an end of the head in a clevis configuration, with opposing pins connecting respective opposite ends of the latch member to the bearing lugs, the pins extending along the latch member elongated axis.
 10. The coupler of claim 8, wherein, in use of the coupler with a rail wagon, the latch member elongated axis extends vertically and the protruding portion extends generally horizontally into the head.
 11. A coupler for a rail wagon, the coupler comprising a coupler body, the body comprising a shank and a head located at an end of the shank, with a coupler latch member being mounted to an end of the head; wherein the latch member comprises a protruding portion for receipt in a recess of the head, and an elongated lateral lug projects to the side of the protruding portion in use, the lateral lug comprising an engagement surface that faces back to the latch member, with the lateral lug engagement surface in use facing a corresponding engagement face located within the head recess. 12-23. (canceled)
 24. A locking block for location in a recess defined in a head of a rail wagon coupler to urge against a protruding portion of a latch member located in the head recess in use so as to restrain the latch member in a closed position, the locking block comprising at least one planar face for respectively engaging at least one of a surface of the latch member protruding portion and a surface of the head, the planar face having a reverse taper with respect to a direction of insertion of the locking block into location between the latch member protruding portion and the head, with one of the latch member surface and head surface being respectively and correspondingly tapered for a mating interface.
 25. The locking block of claim 24, comprising first and second planar faces for respectively engaging a surface of the latch member protruding portion and a surface of the head, and wherein each of the first and second planar faces have a reverse taper with respect to a direction of insertion of the locking block into location between the latch member protruding portion and the head, with the latch member surface and head surface being respectively and correspondingly tapered for a mating interface.
 26. The locking block of claim 25, wherein in use, when the coupler is generally horizontal, the block face that engages the latch member is inclined to a vertical plane but is generally parallel to a longitudinal axis through the coupler, and the block face that engages the head is aligned with the vertical plane but is generally inclined to the coupler longitudinal axis. 27-28. (canceled)
 29. The coupler of claim 11, further comprising an upper projecting lug that extends in use upwardly from the protruding portion, wherein the upper lug is elongated and curved and comprises a curved planar engagement surface that faces back to the latch member, the upper lug able to engage a correspondingly curved engagement surface defined whin the head recess, and wherein the lateral lug is contiguous with the upper lug.
 30. The coupler of claim 11, further comprising a locking block for location in the head recess between the latch member protruding portion and the head, the locking block being adapted to restrain the latch member in a closed, latched position.
 31. The coupler of claim 30, wherein the locking block comprises a planar face for engaging a surface of the latch member protruding portion, and wherein the planar face has a reverse taper with respect to a direction of insertion of the locking block into the head recess, with the latch member surface being correspondingly tapered for a mating interface.
 32. The coupler of claim 11, wherein the latch member is elongated and is mounted to the head so as to pivot around an elongated axis of the latch member, with the protruding portion extending laterally from the latch member with respect to its elongated axis.
 33. The coupler of claim 32, wherein the latch member is pivotally mounted to the head via spaced opposing bearing lugs that protrude from an end of the head in a clevis configuration, with opposing pins connecting respective opposite ends of the latch member to the bearing lugs, the pins extending along the latch member elongated axis.
 34. The coupler of claim 32, wherein, in use of the coupler with a rail wagon, the latch member elongated axis extends vertically and the protruding portion extends generally horizontally into the head. 